Bin-Type bulk liquid containers are generally used for the storage and transportation of large quantities of liquids. The containers comprise a rigid carton, usually constructed of corrugated cardboard or other lightweight fiber or paper materials, and are manufactured in standard sizes: 55 gallon, 110 gallon, 220 gallon, 275 gallon, 300 gallon, and 330 gallon capacities. The dimensions of the containers allow for mounting on standard-sized, rectangular loading pallets. These bulk containers offer substantial economic advantages over traditional metal drums or barrels because the bulk containers weigh less and are made from recyclable materials. Furthermore, the containers are manufactured in interlocking geometric sizes and shapes which simplify storage and minimize wasted storage space. For instance, intermediate size bulk containers may be stacked several units high. These advantages lead to lower freight rates, manufacturing ease, ease of operation, lower overall costs, and substantial space savings.
A bulk container for storing or transporting liquids also conventionally comprises a polyethylene bag placed within the rigid carton to hold the liquid product. The bag normally has a spigot, valve, or sealed tube molded into its side to permit evacuation of the liquid from the filled bag. When the bag is positioned inside the carton, this evacuation element projects through a small opening or orifice in the side of the carton, near the bottom.
The carton effectively causes the liquid-filled polyethylene bag to conform to the shape of the carton. The bag is susceptible to rupture during transport, however, due to inertial movement or "splashing" of the liquid within the bag. The hydraulic energy of the liquid during movement sometimes causes the bag to stretch and crack. This problem is more significant when the bag is filled with liquids that are not too viscous.
The polyethylene bag is subject to increased stretching and an increased possibility of rupture if an air space is left between the filled bag and the top of the carton. The fluid transport and storage industry deals with this problem by filling this air space with dunnage to absorb some of the hydraulic energy of the liquid. The dunnage used is lightweight and compressible, and prevents the fluid-filled bag from shifting significantly during transportation. The most commonly used dunnage products are sealed-air foam, which is foamed into the headspace at the time the bag is filled with liquid, or 1.6 to 2.3 density foam sheeting cut to fit the space.
As previously pointed out, an evacuation element in the form of a spigot, valve or tube is used to drain liquid from the container. The element is connected to the polyethylene bag within the carton, and is usually positioned on a side wall close to a bottom edge. In order to protect the structural integrity of the container and minimize the possibility of leakage and damage to the evacuation element, the element is usually mounted a short distance above the bottom.
Because of the position of the evacuation element, complete product evacuation cannot be achieved without moving the container. The container must be tipped forward, toward the element, in order to drain the liquid which remains in the bag below the level of the element. Moving the container in this fashion is inconvenient to the user, especially when the container is of a larger size. Moreover, tipping the container forward is nearly impossible if containers are stacked several high. Unstacking them to drain them reduces the economic advantage offered by this storage configuration, i.e., adds to the otherwise low costs which are a significant advantage of bulk containers. Finally, if all the liquid product in the bag is not drained, the user incurs a substantial amount of waste. In the larger bulk container sizes, 10 to 20 gallons of liquid may remain in the bottom of the bag if the container is not tipped.